Mellotronists

howdy everyone:
i've recently started hearing an intermittent clicking sound (occurring at regular intervals in 
sync with the wheel) from the left side somewhere inside my MK VI (can't pinpoint from 
where just yet). i was wondering if anybody knew anything about this and could provide 
advice on how to get rid of it.
any help would be greatly appreciated
thanks and keep on 'tronning
-J